Open sourcing an internal repository with extensive, ongoing work on it is always a difficult affair, because you're creating a second source of truth. (It isn't just how you manage external contributions, but also workflows like releases and CI.)

I wouldn't consider this to be a problem.

It means they haven't (yet?) transitioned to open-first and it'll require proving themselves that they'll do open-first development before trusting them. Not willing to bet my work on a product where the governance isn't open but everything is driven by and for a single company's needs.